U.S. patent application number 09/986190 was filed with the patent office on 2003-01-30 for building method of overhead infrastructure.
This patent application is currently assigned to Daimei Telecom Engineering Corp.. Invention is credited to Barker, Makiko, Komine, Zenichi, Kuno, Akira, Misaku, Katsunori, Misaku, Kazue, Nimiya, Takayuki, Takagi, Kaoru, Takemura, Norio.
Application Number | 20030020056 09/986190 |
Document ID | / |
Family ID | 19061538 |
Filed Date | 2003-01-30 |
United States Patent
Application |
20030020056 |
Kind Code |
A1 |
Nimiya, Takayuki ; et
al. |
January 30, 2003 |
Building method of overhead infrastructure
Abstract
Disclosed is a method for building an overhead infrastructure
capable of minimizing loads to utility poles, increasing suspension
spaces on the utility poles, decreasing costs for constructing the
overhead infrastructure, and improving an appearance and
maintenance workability thereof. The method comprises a step of
drawing a tensile line between utility poles, a step of putting
around the tensile line a plastically deformable coil having a
metal wire formed in a spiral shape and synthetic resin coated on a
surface of the metal wire, a step of elongating the coil until its
plastic deformation so as to form a basic construction with a
series of overhead cableway capable of holding a plurality of
overhead lines inside the spiral of the coil, and a step of
extending an overhead line in an empty space of the overhead
cableway on demand.
Inventors: |
Nimiya, Takayuki; (Tokyo,
JP) ; Komine, Zenichi; (Tokyo, JP) ; Kuno,
Akira; (Tokyo, JP) ; Takemura, Norio; (Tokyo,
JP) ; Misaku, Katsunori; (Ayase-shi, JP) ;
Misaku, Kazue; (Ayase-shi, JP) ; Takagi, Kaoru;
(Ayase-shi, JP) ; Barker, Makiko; (Ayase-shi,
JP) |
Correspondence
Address: |
RADER, FISHMAN & GRAUER, PLLC
Suite 501
1233 20th Street, N.W.
Washington
DC
20036
US
|
Assignee: |
Daimei Telecom Engineering
Corp.
|
Family ID: |
19061538 |
Appl. No.: |
09/986190 |
Filed: |
November 7, 2001 |
Current U.S.
Class: |
254/134.3CL |
Current CPC
Class: |
H02G 1/04 20130101 |
Class at
Publication: |
254/134.3CL |
International
Class: |
B65H 059/00 |
Foreign Application Data
Date |
Code |
Application Number |
Jul 30, 2001 |
JP |
2001-229147 |
Claims
What is claimed is:
1. A method for building an overhead infrastructure comprising a
step of drawing a tensile line between utility poles, a step of
putting around the tensile line a plastically deformable coil
having a metal wire formed in a spiral shape and synthetic resin
coated on a surface of the metal wire, a step of elongating the
coil until its plastic deformation so as to form a basic
construction with a series of overhead cableway capable of holding
a plurality of overhead lines inside the spiral of the coil, and a
step of extending an overhead line in an empty space of the
overhead cableway on demand.
2. The method for building the overhead infrastructure according to
claim 1, wherein a plurality of overhead lines, respectively
managed by each of a plurality of business conductors, are
accommodated in the overhead cableway.
3. The method for building the overhead infrastructure according to
claim 1, wherein a plurality of overhead lines, respectively
managed by each of a plurality of business conductors, are
accommodated in the overhead cableway, and an administrator
provides the business conductors with rights for using the overhead
cableway for rent or for sale with a fee according to a number and
weight of the overhead lines managed by each of the business
conductors.
4. The method for building the overhead infrastructure according to
any one of claims 1 to 3, wherein for the installation of the basic
construction, tensile strength of the tensile line is set based on
the maximum load estimated from an amount of the overhead lines
possibly inserted in the overhead cableway.
5. The method for building the overhead infrastructure according to
any one of claims 1 to 3, wherein for the installation of the basic
construction, a size of the overhead cableway is set based on an
estimated demand for the overhead lines.
6. The method for building the overhead infrastructure according to
any one of claims 1 to 3, wherein distribution of the overhead
lines is carried out through gaps of the coil between the utility
poles.
Description
BACKGROUND OF THE INVENTION
[0001] The present invention concerns a method for building an
overhead infrastructure with extended overhead lines such as
various cables and, more particularly, a method for building an
overhead infrastructure capable of minimizing loads to utility
poles, increasing suspension spaces on the utility poles,
decreasing costs for constructing the overhead infrastructure, and
improving an appearance and maintenance workability thereof.
[0002] In general, when various cables such as communication cable
or the like are to be erected, a messenger wire is put up as a
tensile line between utility poles, and metal hangers such as cable
hangers are attached one by one to this messenger wire with an
interval of 50 to 60 cm for hanging cables in parallel. A complex
cable having a messenger wire combined with a cable may be used
instead.
[0003] Erection of the cables has been independently operated by
each of business conductors. For example, when two business
conductors erect communication cables in the same section, those
erection works may be separately done all the way. Therefore,
whenever a business conductor erects a cable between utility poles,
it is a common practice to extend a messenger wire.
[0004] In such a practice as described above, there have been
problems raised as follows. First, since the weight of the
messenger wire and attachment metal parts and the tension of the
messenger wire become more than necessary, a load to utility poles
is increased, thereby making the utility poles easier to cause
breakage or collapses. If supporting lines are added to the utility
poles, the breakage and the collapses can be prevented. The
supporting lines, however, are obliquely drawn from an upper part
of the utility pole to the ground, so it is not always possible to
have spaces for installing the supporting lines.
[0005] Moreover, since points for suspending cables, which are
occupied by each of business conductors, are set on the utility
pole with a predetermined interval in a vertical direction, there
is a lack of suspension spaces on the utility poles. Besides, a
number of cables and lead-in wires are flooded around the utility
poles, thereby deteriorating an appearance and maintenance
workability of the utility poles. Furthermore, each of the business
conductors usually complete by itself erection works including
operations for drawing a messenger wire, thereby causing a problem
to increase costs for construction.
SUMMARY OF THE INVENTION
[0006] It is an object of the present invention to provide a method
for building an overhead infrastructure capable of minimizing loads
to utility poles, increasing suspension spaces on the utility
poles, decreasing costs for constructing the overhead
infrastructure, and improving an appearance and maintenance
workability thereof.
[0007] The method for building the overhead infrastructure of the
present invention to attain the aforementioned object comprises a
step of drawing a tensile line between utility poles, a step of
putting around the tensile line a plastically deformable coil
having a metal wire formed in a spiral shape and synthetic resin
coated on a surface of the metal wire, a step of elongating the
coil until its plastic deformation so as to form a basic
construction with a series of overhead cableway capable of holding
a plurality of overhead lines inside the spiral of the coil, and a
step of extending an overhead line in an empty space of the
overhead cableway on demand.
[0008] As described above, to the tensile line drawn between
utility poles, the basic construction with the series of overhead
cableway capable of holding a plurality of overhead lines is
installed by using the plastically deformable coil, and then an
overhead line is extended in an empty space of the overhead
cableway on demand. Thus, there is no necessity to draw a tensile
line such as a messenger wire between the utility poles when the
overhead line is extended. Therefore, it is possible to avoid that
the weight of the messenger wire and attachment metal parts and the
tension of the messenger wire become more than necessary, thereby
minimizing loads to utility poles. As a result, without supporting
lines added to the utility poles, breakage and collapse of utility
poles hardly happen, thereby improving safety.
[0009] Since the overhead cableway is capable of holding a
plurality of the overhead lines, it is possible to increase
suspension spaces on the utility poles. Moreover, the overhead
lines may be arranged in the overhead cableway, thus an appearance
and maintenance workability of the utility poles can be improved.
Furthermore, the basic construction may be used by a plurality of
business conductors, so the work by each of business conductors to
extend a tensile line such as a messenger wire may be omitted,
thereby decreasing costs for constructing the overhead
infrastructure.
[0010] In the present invention, it is preferable to form a common
use system of an overhead infrastructure, by accommodating a
plurality of overhead lines, respectively managed by each of a
plurality of business conductors, in the overhead cableway. In the
common use system, a plurality of overhead lines, respectively
managed by each of a plurality of business conductors, are
accommodated in the overhead cableway, and an administrator
provides the business conductors with rights for using the overhead
cableway for rent or for sale with a fee according to a number and
weight of the overhead lines managed by each of the business
conductors. That is, this invention aims to build the overhead
infrastructure for its common use, and provides a common use method
of the overhead infrastructure as a preferable embodiment.
[0011] As a result, a business conductor who does not have an
infrastructure such as utility poles and tensile lines may be able
to easily start a business utilizing overhead lines. For example,
communication business conductors, without such a common use
system, can not erect an overhead line such as a communication
cable and the like unless an infrastructure including utility poles
and tensile lines has been built. However, using the above
described common use system, they can drastically reduce an initial
investment cost since only the overhead line need to be prepared
and erected.
[0012] The administrator who administrates the basic construction
rents or sells the empty spaces in the overhead cableway to the
business conductors for the purpose of extending the overhead
lines, and, if necessary, remove a useless overhead line from the
overhead cableway to make an empty space again. Of course, a part
of core lines contained in the overhead line can be rented or sold
to the business conductors.
[0013] According to the present invention, there is a benefit that
a plurality of overhead lines extended between utility poles can be
totally managed. For the installation of the basic construction,
tensile strength of the tensile line is preferably set based on the
maximum load estimated from an amount of the overhead lines
possibly inserted in the overhead cableway. Also, for the
installation of the basic construction, a size of the overhead
cableway is preferably set based on an estimated demand for the
overhead lines. When these administrative methods are introduced,
the overhead infrastructure can be built with the most preferred
appearance.
[0014] When the overhead lines are required to diverge between the
utility poles, it is preferable that distribution of the overhead
lines is carried out through gaps of the coil. That is, the
overhead cableway formed of the coil allows the distribution of the
line through gaps of the coil, so it will contribute to further
improving the appearance and the maintenance workability.
[0015] In the present invention, as a tensile line, a messenger
wire made of a plurality of twisted steel wires, a complex cable
integrating messenger wire and cable (so-called SS type cable) or
others can be selected. On the other hand, the overhead line
includes not only various cables such as a communication cable, a
television cable, a power cable and the like, that contain a number
of metallic wires or optical fibers in a bundle but also lead-in
wires to offices or houses such as a power line, telephone line and
the like.
BRIEF DESCRIPTION OF DRAWINGS
[0016] FIG. 1 shows an example of plastically deformable coil used
for the overhead infrastructure building method of the present
invention; FIG. 1(a) is a side view of the coil, FIG. 1(b) a
cross-section of a resin coated wire composing the coil, and FIG.
1(c) a side view of the resin coated wire.
[0017] FIG. 2 shows an example of the coil extension device used
for the overhead infrastructure building method of the present
invention; FIG. 2(a) is a side-view of non-elongated coil, and FIG.
2(b) a side-view of elongated coil.
[0018] FIG. 3 shows another coil extension device used for the
overhead infrastructure building method of the present invention;
FIG. 3(a) is a side-view of non-elongated coil, and FIG. 3(b) a
side-view of elongated coil.
[0019] FIG. 4 shows a sate of cable erection by the overhead
infrastructure building method of the present invention; FIG. 4(a)
shows a side-view, and FIG. 4(b) a view along the line X-X.
[0020] FIG. 5 is a side view showing another sate of cable erection
by the overhead infrastructure building method of the present
invention.
[0021] FIG. 6 is an enlarged view of a portion Y in the FIG. 5.
DETAILED DESCRIPTION OF PREFERRED EMBODIMENT
[0022] Now, the present invention will be described in detail
referring to attached drawings.
[0023] FIG. 1 shows an example of plastically deformable coil used
for the overhead infrastructure building method of the present
invention. As shown in FIG. 1(a) to FIG. 1(c), a plastically
deformable coil 1 has a structure wherein a resin coated wire 1A
made by coating around a metal wire 1a with synthetic resin 1b is
formed in a spiral shape. The cross-section shape of the resin
coated wire 1A is preferably non-circular, including polygons such
an octagon or others. When the resin coated wire 1A is twisted so
as to rotate the non-circular shape spirally in the longitudinal
direction of the metal wire 1a, the wind sound generated during the
cable erection may be reduced. The coil 1 has a length L in the
non-elongated state without load before used for the cable
erection, however, it will have a state elongated to a length
corresponding to one span between electric utility poles during the
cable erection. When the elongated coil is short or too long for
one span between electric utility poles, the coil 1 may be cut off
or prolonged.
[0024] The coil 1 mentioned above is provided with such property
that the metal wire 1a deforms plastically, when the coil is
elongated from its non-elongated length L. To be more specific,
when the coil is elongated by 10 times or more than its
non-elongated length L, the coil 1 shrinks from the diameter D and,
at the same time, it deforms plastically so that the length after
elongation will be kept. If this metal wire 1a deforms at an
elongation less than 10 times of its non-elongated length L, it
becomes difficult to elongate the coil 1 so as to keep the spiral
pitch at constant interval.
[0025] To provide the aforementioned coil 1 made of complex
material of the metal wire 1a and the synthetic resin 1b with said
property, the material of the metal wire 1a and the synthetic resin
1b may be selected properly and the cross-section ration of the
metal wire 1a at the resin coated wire 1A may be set properly.
[0026] As the metal wire 1a, iron wire, copper wire, aluminum wire
or the like of 1.0 to 5.0 mm in diameter can be used. Especially,
it is preferable to used iron wire to provide the most appropriate
plastic deformation for cable erection. Besides, it is advantageous
to use galvanized wire to prevent from corrosion. If the diameter
of the metal wire 1a is less than 1.0 mm, its capability to hold
the cable becomes insufficient and, on the contrary, if it is more
than 5.0 mm, the coil itself becomes heavy unfavorably.
[0027] It is preferable to set the ratio of the cross-section of
the metal wire to the cross-section of the resin coated wire is
equal or superior to 25%. If the ratio of the cross-section of the
metal wire is less than 25%, elastic deformation of the synthetic
resin 1b makes plastic deformation of the metal wire 1a difficult.
Note that the cross-section shape of the metal wire 1a is not
specially limited and, in addition to the circle as shown in the
drawing, it can take oval, triangular, square, octagonal or other
polygonal shape.
[0028] On the other hand, as synthetic resin 1b, thermoplastic
resin such as polyester, polyamide, polyolefin can be used. Among
these thermoplastic resins, polyester is especially preferable. As
this polyester, polyethylene terephthalate, polybutylene
terephthalate, or copolymer polyester obtained by copolymerization
of them with a third component such as adipic acid, isophthalic
acid, isophthalic sulfonate and polyethylene glycol can be
cited.
[0029] Moreover, as polyamide, nylon 6, nylon 66, nylon 610, nylon
612, nylon 11, nylon 12 and copolymer polyamide made by combination
of components of respective nylon can be cited. As polyolefin,
polyethylene, polypropylene and the like can be cited.
[0030] Obviously, these thermoplastic resins may comprise as
desired heat resistant agent, weather resistant agent,
photoresistant agent, antioxidant, antistatic additive, smoother,
dye or other normal additive components as necessary.
[0031] The non-elongated length L of the coil 1 is preferably short
from the viewpoint of handling; however, its workability will be
favored if it is set to elongate at least up to 1 span between
utility poles during cable erection. For this effect, when the
non-elongated length L is within the range of 500 to 2000 mm, the
elongated length is preferably set a range of 10 to 80 times,
especially 20 to 60 times of that length L. Moreover, the outer
diameter D of the non-elongated coil 1 is advantageously set to a
range of 20 to 120 mm.
[0032] Now, the overhead infrastructure building method of the
present invention will be described. In the present invention,
after a messenger wire is drawn as a tensile wire between utility
poles, the aforementioned coil 1 is set around the messenger wire
and elongated along the messenger wire. For the elongation of the
coil 1, a coil extension device shown in FIG. 2 or FIG. 3 can be
used to extend the aforementioned coil 1.
[0033] In FIG. 2, a coil extension device 10 has a structure made
by assembling a bone member 11 in a cone shape, and is provided
with a reducing aperture 12 smaller than the outer diameter of the
coil 1 at the apex of the cone. Moreover, the coil extension device
10 is made of two members divided along the cone slant, and these
both members can open or close by means of a hinge 13 and,
moreover, can be cramped in closed state by means of a bolt 14.
[0034] When the coil 1 is extended by the aforementioned coil
extension device 10, as shown in FIG. 2(a), first the coil 1 is
inserted outside around a messenger wire W drawn between utility
poles P, P, then one end side of the coil 1 is attached to the
messenger wire W with a cram member 2, then the coil extension
device 10 provided with the reducing aperture 12 smaller than the
outer diameter of the coil 1 is disposed at one end side of the
coil 1. To be more specific, the reducing aperture 12 is positioned
at the one end side of the coil 1 and the coil extension device 10
is installed so that the cone section of the bone member 11 covers
the coil 1. Then, as shown in FIG. 2(b), the coil extension device
10 is pulled toward the other end side of the coil 1 along the
messenger wire W, by means of a traction wire 15 attached to the
cone bottom of the bone member 11, and the coil 1 is elongated
until its plastic deformation all the way being discharged from the
reducing aperture 12. In order to operate from the ground the coil
extension device 10 moving along the messenger wire W, a hook 16 is
hung on the messenger wire W, and a ground operation rope 17 is
attached to this hook 16. It is also advantageous to attach the
other end side of the coil 1 to the hook 16.
[0035] When the coil 1 is extended using the coil extension device
10 as mentioned above, the pitch and the outside diameter of the
elongated coil 1 can be set based on the size of the reducing
aperture 12 and, moreover, the coil 1 can be extended evenly along
its total length. As the coil extension device 10 is assembled of
the bone member 11, the coil 1 can be handled easily through its
gap, and moreover, as it is light, it will not apply much load to
the messenger wire W. Note that, when the coil 1 is extended with
help by the coil extension device 10, a cable may be extended
inside the coil 1 at the same time.
[0036] On the other hand, in FIG. 3, a coil extension device 20 has
a structure made by assembling a bone member 21 in a cone shape,
and is provided with a reducing aperture 22 smaller than the outer
diameter of the coil 1 at the apex of the cone. Moreover, the coil
extension device 20 is made of two members divided along the cone
slant, and these both members can open or close by means of a hinge
23 and, moreover, can be cramped in closed state by means of a bolt
24.
[0037] When the coil 1 is extended by the aforementioned coil
extension device 20, as shown in FIG. 3(a), first the coil 1 is
inserted outside around a messenger wire W drawn between utility
poles P, P, then one end side of the coil 1 is attached to the
messenger wire W with a cramp member 2, then the coil extension
device 20 provided with the reducing aperture 22 smaller than the
outer diameter of the coil 1 is disposed at the other end side of
the coil 1. To be more specific, the reducing aperture 22 is
positioned at the other end side of the coil 1 and the coil
extension device 20 is installed so that the cone section of the
bone member 21 covers the coil 1.
[0038] Then, as shown in FIG. 3(b), the other end side of the coil
1 is connected to a leading chariot 26 running freely over the
messenger wire W, then the other end side of the coil 1 is drawn by
the leading chariot 26 along the messenger wire W, with the
position of the coil extension device 20 fixed with respect to the
utility pole P using a fixing rope 25 attached to the cone bottom
of the bone member 21, and the coil 1 is elongated until its
plastic deformation all the way being discharged from the reducing
aperture 22. This leading chariot 26 permits only the advance, and
a brake acts during the regression. In order to operate from the
ground the leading chariot 26 moving along the messenger wire W, a
ground operation rope 27 is attached to the leading chariot 26.
Note that such leading chariot 26 may also be applied to the method
shown in FIG. 2.
[0039] When the coil 1 is extended using the coil extension device
20 as mentioned above, the pitch and the outside diameter of the
elongated coil 1 can be set based on the size of the reducing
aperture 22 and, moreover, the coil 1 can be extended evenly along
the total length. As the coil extension device 20 is assembled of
the bone member 21, the coil 1 can be handled easily through its
gap, and moreover, as it is light, it will not apply much load to
the messenger wire W. In addition, if the tip of the cable C is
connected to the leading chariot 26, the cable C can be extended at
the same time as the extension of the coil 1.
[0040] FIG. 4 shows a sate of cable erection by the overhead
infrastructure building method of the present invention. As shown
in FIG. 4(a) and FIG. 4(b), according to the overhead
infrastructure building method of the present invention, a
plastically deformable coil 1 is used, the coil 1 is inserted
outside around the messenger wire W drawn between utility poles,
and then the coil is elongated until its plastic deformation so as
to form a basic construction with a series of overhead cableway S
capable of holding a plurality of overhead lines such as the cable
C inside the spiral of the coil. When the basic construction is
installed, a cable C required at the time may be extended
simultaneously. At this time, a plurality of cables C may be
extended together. Then, another cable C will be extended in an
empty space of the overhead cableway S on demand.
[0041] For the installation of the basic construction, tensile
strength of the messenger wire W is set based on the maximum load
estimated from an amount of the cables C possibly inserted in the
overhead cableway S. That is, since the number of cables C possibly
inserted in the overhead cableway S is substantially determined by
the section area of the overhead cableway S, the maximum load to
the messenger wire with cables C inserted in the overhead cableway
without any gaps can be estimated by taking the number of the
cables C, the weight of the cables C, the distance between the
utility poles and the like into account. Then, the tensile strength
of the messenger wire W may be set so as to bear the estimated
maximum load.
[0042] Moreover, for the installation of the basic construction, a
size of the overhead cableway S is set based on an estimated demand
for the cables C. That is, the demand for cables C that may be
required in the future is estimated according to the civil planning
in the region and the situation of the utility pole installation.
Then, the size of the overhead cableway may be set so as to satisfy
the estimated demand.
[0043] The estimates on the maximum load and the demand do not
necessarily have to be accurate. If the maximum load is larger than
the estimate, the number of the cables C extended in the overhead
cableway may be lowered from the initially planned one. If the
demand for the cables C is more than the estimate, the basic
construction may be added.
[0044] According to the aforementioned method for building the
overhead infrastructure, the basic construction with the series of
overhead cableway S capable of holding a plurality of cables C is
installed in advance, and then a cable C is extended in an empty
space of the overhead cableway S on demand. Thus, there is no
necessity to draw a messenger wire W between the utility poles when
the cable C is extended. Therefore, it is possible to avoid that
the weight of the messenger wire W and attachment metal parts and
the tension of the messenger wire W become more than necessary,
thereby minimizing loads to utility poles. As a result, without
supporting lines added to the utility poles, breakage and collapse
of utility poles hardly happen, thereby improving safety.
[0045] Since the overhead cableway S is capable of holding a
plurality of the cables C, it is possible to increase suspension
spaces on the utility poles. That is, in the conventional skill,
one cable is supported by one messenger wire, and suspension points
are set on the utility pole with a predetermined interval in the
vertical direction. Therefore, there was a lack of suspension
spaces. On the other hand, the aforementioned overhead cableway S
holds a plurality of cables in bundle, so the number of required
suspension points may be reduced under a condition where the number
of cables is constant. Because of this, it is possible to have more
suspension spaces on the utility poles and to erect more
cables.
[0046] Moreover, a plurality of cables C may be arranged in the
overhead cableway S, thus an appearance and maintenance workability
of the utility poles can be improved. Furthermore, the basic
construction may be used by a plurality of business conductors, so
the work by each of business conductors to extend a messenger wire
W may be omitted. Therefore, costs for constructing the overhead
infrastructure may be reduced.
[0047] Moreover, a plurality of cables C, respectively managed by
each of a plurality of business conductors, are accommodated in the
overhead cableway S to form the common use system of overhead
infrastructure, thus the aforementioned various profits can be
shared by business conductors. In this case, an administrator of
the basic construction may provide the business conductors with
rights for using the overhead cableway S for rent or for sale with
a fee according to a number and weight of the cables C managed by
each of the business conductors. Of course, the administrator of
the basic construction may join the communication business
utilizing the cable C.
[0048] In the overhead infrastructure building work using the
aforementioned coil 1, the following merits may be obtained. First
of all, all suspension points for hanging the cable C through a
helical loop with a constant interval can be formed, and the cable
C can be extended by only one operation of simply elongating the
coil 1 between utility poles. Moreover, once the cable C is
extended, the coil 1 can be used as cable fixing hanger as it is.
Consequently, it makes unnecessary to erect temporarily the cable C
by means of a cable extension jig such as pulley, and simplifies
the operation to attach a number of metal hangers one by one at a
constant interval as in the conventional cable erection.
[0049] Moreover, as the metal wire 1a deforms plastically when the
coil 1 is elongated, the plastically deformed metal cable 1a
prevents the cable C from drooping, even if a coil fastener to the
messenger wire W is off, or a part the coil 1 is cut off. Besides,
the cable does not shrink to its original length even if the coil 1
fixed end comes off, or the elongated non-fixed end is released
accidentally during the cable erection work. Therefore, the cable C
can be held in a stable state during and after the erection.
Moreover, even if a fire breaks out in the vicinity of the cable
erection emplacement, causing the cable 1 inflamed and the
synthetic resin 1b burned out, the cable C can be held by the metal
wire 1a.
[0050] FIG. 5 shows another sate of cable erection by the overhead
infrastructure building method of the present invention. In this
embodiment, the basic construction with a series of overhead
cableway S is formed along the messenger wire drawn between the
utility poles P, P with the use of the coil 1, and after the
communication cable C is extended, a lead-in wire C.sub.1 is
further added in the empty space of the overhead cableway S on
demand.
[0051] In this case, the lead-in wire C.sub.1 pulled out from a
connecting terminal box B may be led along the messenger wire W in
the overhead cableway S and distributed towards a house 30 through
a gap of the coil 1 at a optional position. When the wire
distributing operation is held, a distributing member 31 is
attached to the messenger wire W, a supporting wire 33 is extended
from the distributing member 31 through a lead-in member 32, and
then the lead-in wire C.sub.1 can be guided along the supporting
wire 33, as shown in FIG. 6.
[0052] According to the aforementioned wire distribution,
appearance and maintenance workability of the utility pole P can be
improved. That is, in the conventional wire distribution, a lead-in
wire pulled out from a connecting terminal box is once led to the
utility pole so as to be fix thereto by a fastener and further
needs to be led to a distributing member attached to the messenger
wire using a supporting wire. Moreover, every lead-in wire is
required with the similar distribution work. Therefore, the lead-in
wires are flooded around the utility poles, causing the appearance
and the maintenance workability drastically deteriorated. On the
other hand, if the basic construction having the overhead cableway
formed by the coil 1 is utilized, those lead-in wires attached
around the utility pole in the conventional skill can be
removed.
[0053] As described above, according to the present invention, a
tensile line is drawn between utility poles, a plastically
deformable coil comprising a metal wire formed in a spiral shape
and synthetic resin coated on a surface of the metal wire is put
around the tensile line, the coil is elongated until its plastic
deformation so as to form a basic construction with a series of
overhead cableway capable of holding a plurality of overhead lines
inside the spiral of the coil, and an overhead line is extended in
an empty space of the overhead cableway on demand. Therefore, it is
possible to have advantages of minimizing loads to utility poles,
increasing suspension spaces on the utility poles, decreasing costs
for constructing the overhead infrastructure, and improving an
appearance and maintenance workability thereof.
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